Page:The American Cyclopædia (1879) Volume IX.djvu/156

 148 ICE ICEBERGS lakes furnish supplies which are carried by rail- road to the cities lying south, and through the Illinois river ice is sent down the Missis- sippi. In the autumn the ice boats come up to the vicinity of Peru, 111., where they are allowed to he frozen in. In the winter they are filled, and in the spring when the ice breaks up they float down with their freight. The ice produced in deep ponds by the severe cold weather of New England is particularly adapt- ed by its hardness and compactness to keep well, while the purity of the water gives it clearness and renders it especially agreeable. The ice obtained from the Kennebec river is most celebrated. That formed upon the shal- low waters of Great Britain is found to be porous and very inferior in durability to that from the United States of the same thickness. The methods of gathering and storing ice are entirely American. When the ice is 9 in. to a foot thick, or if for exportation 20 in. thick, the snow, if there he any, is cleared ofi the surface with wooden scrapers, each drawn -by one horse. Another scraper armed with a steel blade planes off the porous upper layer to the depth of 3 in. or more if necessary. The surface is then marked off in large squares by a sort of plough drawn by a horse, which cuts a groove about 3 in. deep. A machine some- what like a harrow, with three or more paral- lel rows of teeth, which may be 22 in. apart, is next drawn along the lines already made, one row of teeth running in the grooves as a guide ; and as many more cuts are made as there are more rows of teeth. This is repeated upon the cross lines, and the whole area is thus cut into small squares. If necessary, a deeper plough is afterward run through all the grooves to in- crease their depth. A row of blocks is then sawn out by hand, and being taken out or thrust under the others, room is made for splitting off the adjoining squares, which is done by an ice spade dropped into the grooves. In very cold weather the ice yields readily to a slight wedging force. The blocks are some- times floated through the canals opened in the ice to the shore, where they are hoisted out ; and they are also sometimes jerked with a hook at the end of a pole up a slide upon a platform placed at the edge of the opening, and from this platform they are slid along on the sleds which convey them away. At the ice houses the blocks are raised often by steam power up an inclined plane to the top of the building, and thence let down another plane to any part within where it is required for pack- ing. The storehouses, huge wooden buildings without windows standing around the edges of the ponds or along the banks of the rivers, present a very singular appearance. They are from 100 to 200 ft. long and very broad, with a capacity sometimes exceeding 20,000 tons. One at Athens on the Hudson holds 58,000 tons, and two at Rockland lake in Orange co., N. Y., hold 40,000 tons each. Around Fresh pond at Cambridge, Mass., there is a largo number of these buildings. Between their walls they are filled in with saw dust. As the season of the ice harvest is short and uncer- tain, the gathering of the crop is conducted with the greatest activity at favorable times. ICEBERGS, and lee Islands, floating masses of ice gathered on the coast of polar regions, and set adrift by force of winds and currents. Many icebergs are produced from glaciers, which, thrust down from the elevated snowy lands in the interior, are moved onward into the deep waters, where the fragments broken off from the advance border are floated away. The edges of glaciers extending many miles along a precipitous coast have been seen to fall with terrific violence into the sea beneath, and at once be transformed into floating islands of ice. These carry with them the masses of rock gathered up by the ice in its progress as a gla- cier, and transport them to new localities in warmer latitudes. (See DILUVIUM, and GLA- CIER.) Ice islands of vast extent are also pro- duced by the breaking up of the great fields of sea-made ice which accumulate along the shores of the frigid waters. In 1817 the ice covering several thousand square miles of the sea N. of Iceland, and chiefly on the E. coast of Greenland, most of which, it is believed, had not been moved for nearly 400 years, was sud- denly broken up and dispersed over the waters of the North Atlantic. Portions of it were carried far to the eastward of the usual range of icebergs from the north, and approached within 800 m. of Ireland, or to Ion. 32 W. The breaking up of this ice led to the expedi- tion of Capt. Ross, the second of the present century in search of a northwest passage, the opinion prevailing that the climate had essen- tially changed, and that the northern seas would continue open. The drift of the north- ern icebergs is with the great polar currents, one of which sets in a S. S. W. direction between Iceland and Greenland, and another along the W. side of Baffin bay, meeting the former near the coast of Labrador. They are brought against the American continent and the W. shores of its bays in consequence of not catch- ing at once the more rapid rotating motion of the earth as they pass upon larger parallels, and so allowing this to slip from under them. The greatest numbers are produced on the W. side of Greenland; and, as observed by Dr. Kane, " perhaps the most remarkable place for the genesis of icebergs on the face of the globe " is at Jacob's bight, an inlet a little N. of Disco island, in about lat. 71 and Ion. 56. From Labrador the ice is floated with the current past Newfoundland, and meeting near the Great Bank the warming influences of the Gulf stream, it usually disappears about lat. 42. The extreme limit is in lat. 40. Some- times the ice is carried as far to the eastward as the Azores. In the southern hemisphere ice- bergs drift still nearer to the equator, being occasionally seen off the cape of Good Hope. As they reach their southern limit.in the north-